The present invention pertains generally to the field of cryo balloon therapy. More particularly, the present invention pertains to cryo balloon therapy catheters for use in causing cold-induced necrosis.
A number of medical conditions may be treated using ablative techniques or devices. Ablative techniques, generally, result in the killing of abnormal tissue at an area of interest. Killing the abnormal tissue may result in an efficacious treatment for a medical condition. For example, atrial fibrillation may be the result of abnormal electrical activity in the left atrium and the pulmonary vein, and may be treatable by ablation of the abnormal tissue within the left atrium and/or the pulmonary vein.
Atrial fibrillation is a serious medical condition that is the result of abnormal electrical activity within the heart. This abnormal activity may occur at regions of the heart including the sino-atrial (SA) node, the atriovenricular (AV) node, the bundle of His, or within other areas of cardiac tissue. Moreover, atrial fibrillation may be caused by abnormal activity within a isolated focal center within the heart. It is believed that these foci can originate within the pulmonary vein, particularly the superior pulmonary veins.
Minimally invasive techniques have been described that use ablation catheters to target the pulmonary vein with the hope of ablating foci having abnormal electrical activity. The techniques typically are characterized by application of energy to cause lesions within the foci or other areas possessing abnormal electrical activity.
Some ablation devices utilize radio frequency (RF) energy for ablation, including the device disclosed in U.S. Pat. No. 6,024,740 to Lesh et al. The RF energy devices may be used to ablate an area of interest with heat. The use of RF energy for ablation may, however, lead to untoward healing responses such as collagen build up at the area of interest after treatment. Moreover, RF ablation of within an atrium may decrease atrial output. A need, therefore, exists for ablative devices and methods that include improved healing responses.
An alternative treatment strategy has been developed that uses cooling energy for ablation. This method, termed cryoplasty or cryo balloon therapy, may be used to cool the lesion to freeze a portion of the affected area. For example, cryo balloon therapy may be used to freeze a lesion within a blood vessel that might otherwise lead to restenosis or recoil.
In addition to its potential utility in preventing and slowing restenosis and addressing recoil, cryo balloon therapy may be used for ablation techniques. For example, cryo balloon therapy may be efficacious in varicose vein treatment of incompetent valves, valvular disease, mitral valve regurgitation therapy, atrial fibrillation, gastric reflux disease, gastro esophageal reflux disease, GURD, esophageal disease, cancer treatment including stomach or uterine cancer, etc.
Uses of cryo balloon therapy include cold-induced killing of cells within the body. When the target area is located within the heart or pulmonary vasculature, it may be important to precisely control the cryo balloon therapy catheter to kill only the desired tissue. Moreover, the irregular shapes of blood vessels and heart chambers may make it difficult to steer a cryo balloon therapy catheter to a precise location. A need, therefore, exists for a cryo balloon therapy catheter with a desirable level of control.
The present invention comprises a refinement of cryo balloon therapy catheters. More particularly, the present invention comprises a cryo balloon therapy apparatus that may be useful in treating a number of medical conditions where cold-induced necrosis may prove beneficial. For example, the cryo balloon therapy apparatus may be used to treat varicose vein treatment of incompetent valves, valvular disease, mitral valve regurgitation therapy, gastric reflux disease, gastro esophageal reflux disease, GURD, esophageal disease, cancer treatment including stomach or uterine cancer, pulmonary vein ablation, etc.
The cryo balloon therapy apparatus may comprise a catheter having a proximal end, a distal end, and a cooling member disposed at the distal end. A pull cord may be coupled to the cooling member. The cryo balloon therapy apparatus may further comprise a sheath that couples the pull cord to the catheter. The use of the sheath in conjunction with the pull cord may allow the cooling member to be easily manipulated and steered by moving the pull cord.
The cooling member may be comprised of an outer member disposed over an inner member. Coolant may be transferred to the inner member in order to cool the cooling member to a temperature appropriate for causing cold-induced necrosis, which may be appropriate for a particular medical procedure. Preferably, coolant may be sprayed onto the inner member in order to facilitate heat transfer between the cooling member and an area of interest.
The cooling member may further comprise an electrode and an electric lead. Alternatively, the cooling member may further comprise a pad printed conductive electrode having an electrical lead. According to this embodiment, the electrode may be used to determine the electrical activity of tissue at an area of interest.
Multiple alternative embodiments of the cooling member are also disclosed. For example, the cooling member may further comprise a support member that may help to prevent the cooling member from rupturing. The cooling member may include a cryo balloon therapy chamber disposed on the mesh cage, the cryo balloon therapy chamber connected to a coolant source. The cryo balloon therapy chamber may further comprise a cryo balloon therapy ring. In another preferred embodiment, the cooling member may further comprise a heat exchange surface that may be slidable, a slidable and rotatable sprayer, or a cryo balloon therapy assembly.